Laser beam guidance systems are used to align a laser beam with an optical boresight, in order to direct the beam to a selected target. Typically, a designated target is viewed through the boresight, and the laser beam is directed to illuminate the target. The reflection of the illumination may be used to guide a weapon to the target. In such a guidance system, the axis of the laser beam must be precisely aligned with the boresight axis, otherwise target designation errors will occur that significantly degrade the accuracy of the weapons delivery system.
One approach to aligning a laser beam with a boresight is described in U.S. Pat. No. 4,385,834, which issued on May 31, 1983 to Richard F. Maxwell, Jr. Maxwell describes a laser beam boresight system that aligns a laser beam's axis with an imaging sensor's viewing axis. The imaging sensor's viewing axis is used as one reference axis. A second laser beam's axis, which is fixed with respect to the first laser beam's axis, is aligned with an electromagnetic source beam axis. A light emitting diode is used as the electromagnetic source. The electromagnetic source beam axis is used as a second reference axis. The first reference axis is fixed with respect to the second reference axis. The angular displacement between the second laser beam's axis and the two, reference axes is detected, and error signals are generated by the detector which are proportional to the angular displacement. The error signals are used to correct the angular displacement, in order to align the second laser beam with the reference beam axes. If the system is properly aligned, the image of the reference source beam in the sensor's display will represent the target at which the first laser beam is directed. However, Maxwell's use of multiple laser beams increases the technical complexity and cost of such a system. An increase in the complexity of such a system is accompanied by a decrease in system accuracy. Furthermore, since the detection of the angular displacement between the second laser beam's axis and the two, reference axes is accomplished at a significant distance from the laser source, a significant amount of noise is generated at the detection stage, which introduces additional errors that further decrease the accuracy of the system. Accordingly, a need exists in the laser beam guidance manufacturing industry for a less complex but more accurate, automatic boresight alignment system.